Video | Jason Collins and Jarron Collins joke on 'Jimmy Kimmel Live'

Jason Collins would always make excuses for why he wasn't interested in the women his twin brother and sister-in-law would set him up with on dates.

Jarron Collins still never figured out that Jason was gay.

Jarron joked Wednesday on ABC's "Jimmy Kimmel Live" that he missed "red flags" about Jason, who recently came out as the first active gay male athlete in one of the major U.S. sports.

The brothers, who played together at Stanford before playing in the NBA, appeared together on the show and discussed how Jason finally let Jarron know after being hesitant for so long.

"He's my best friend and any time you come out to someone, you always have that apprehension that they're going to reject, even though I knew that that wasn't going to be the case," Jason Collins said.

Jarron was supportive but said he botched his response at first, saying things such as "Are you sure?" and "Since when?"

"He's my twin brother, of course I was going to be supportive of him all the time," Jarron said.

Jarron said since Jason's announcement, he's been approached by other men asking if he is Jason. To help clear that up, Kimmel gave him a T-shirt that read: "I'm the straight one."